Do you have a paypal account? If you do, its unlikely that Lloyds would have blocked paypal. So I’d expect you would be able to buy a manual goodybag through paypal, even if the paypal is funded through Lloyds Bank.
However, giffgaff would still appear as part of the paypal transaction ID, so it’s possible Lloyds might have programmed a block on that too.
If that’s the case, then only a different bank, or a shop giffgaff voucher, would be possible. And if you’re using a voucher for the payment, take care to buy a goodybag (43430 option 2) not credit.